MathDB
OEHF is parallelogram

Source: Junior Olympiad of Malaysia Shortlist 2015 G1

July 17, 2015
geometryparallelogram

Problem Statement

Given a triangle ABCABC, and let E E and F F be the feet of altitudes from vertices B B and C C to the opposite sides. Denote O O and H H be the circumcenter and orthocenter of triangle ABC ABC . Given that FA=FC FA=FC , prove that OEHF OEHF is a parallelogram.
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